import * as path from "@std/path";

import { createSingleton, generateTimeStringForFileName } from "./util.ts";

export class Logger {
  constructor(public readonly path: string) {}

  warn(message: string) {
    console.log(message);
  }

  generateLogFilePath(
    prefix: string = "",
    suffix: string = "",
    instant?: Temporal.Instant | Date,
  ): string {
    return path.join(
      this.path,
      `${prefix}-${generateTimeStringForFileName(instant)}-${suffix}`,
    );
  }

  openLogFile(
    prefix: string = "",
    suffix: string = "",
    instant?: Temporal.Instant | Date,
  ): Promise<Deno.FsFile> {
    const logPath = this.generateLogFilePath(prefix, suffix, instant);
    return Deno.open(logPath, {
      read: false,
      write: true,
      append: true,
      create: true,
    });
  }

  async logProgramOutput(
    process: Deno.ChildProcess,
    program: string,
    instant?: Temporal.Instant | Date,
  ): Promise<void> {
    const stdoutFile = await this.openLogFile(program, "stdout", instant);
    const stderrFile = await this.openLogFile(program, "stderr", instant);

    process.stdout.pipeTo(stdoutFile.writable);
    process.stderr.pipeTo(stderrFile.writable);
  }
}

export const [getLogger, setLogger] = createSingleton<Logger>("Logger");